The present invention relates to laryngeal airway devices. More specifically, the present invention relates to improved geometric and design configurations for laryngeal airway devices.
It is common practice to use an airway device known as a laryngeal mask for the administration of anesthetic and ventilation gases to a patient. These airways comprise a tube with an inflatable mask or cuff at one end, the tube being inserted in the patient's mouth so that one end is located in the hypopharynx and so that the mask forms a seal in this region with the surrounding tissue. Laryngeal masks are provided by many suppliers.
The laryngeal airway is a device that fills the gap between tracheal intubation and the use of a face mask. The laryngeal airway device is inserted blindly into the pharynx and forms a low pressure seal around the laryngeal inlet. It is minimally stimulating to the airway, thus avoiding the unwanted sympathetic stimulation associated with laryngoscopy. The laryngeal airway device provides a way of establishing an airway during anesthesia in both adults and children, and plays a useful role in management of the difficult airway.
As show in FIG. 1, a common laryngeal airway device is constructed of medical-grade silicone rubber with no latex in any part. This allows the laryngeal airway device to withstand repeated autoclaving. The device has a shaft or airway tube 1 ranging from 5.25 to 12 mm in internal diameter, depending on the size of the laryngeal airway device. The shaft is fused at an angle to a distal elliptical spoon-shaped mask 2 with an inflatable rim or cuff resembling a miniature face mask. The shaft opens into the concavity of the ellipse via an aperture having aperture bars 3 across the opening to prevent the epiglottis from falling back and blocking the lumen. Various different size laryngeal airway devices are available to accommodate different size patients, from neonates to adult patients.
When correctly positioned, the tip of the laryngeal airway device cuff lies at the base of the hypopharynx against the upper esophageal sphincter, the sides lie in the pyriform fossae, and the upper border of the mask lies at the base of the tongue, pushing it forward. The epiglottis often lies within the bowl of the laryngeal airway device, but the device functions satisfactorily with the epiglottis in the upright horizontal or downfolded position. When the cuff is around the opening to the larynx, a syringe connects to the valve 4 to inject air into the cuff via the inflation line 5 to inflate the cuff, such that no gap is present between the cuff and the larynx. The inflation line 5 meets the cuff 2 at an inflation line inlet 8, which inlet 8 is typically also the mold extraction point or orifice used during the forming of the cuff 2. An inflation line balloon 6 reflects the degree of inflation of the cuff. Typically, the airway tube includes a securely attached 15 mm connector 7 at its proximal end.
However existing laryngeal airway devices suffer from various shortcomings. For example, the aperture bars across the airway opening prevent the entry of other devices, such as bronchoscopes and/or endotracheal tubes into the airway passage. The spoon-shaped cuff is inflated at its proximal end by a separate inflation line. In some devices, the inflation line inlet at the proximal end of the cuff is also the same as the mold extraction orifice used to form the cuff, and protrudes away from the surface of the cuff, resulting in a nonsmooth external surface for the cuff. The separate inflation line needs to be carefully handled as the laryngeal airway device is inserted into a patient's airway. It has been reported by many that the cuff folds back on itself as the laryngeal airway device is being inserted. The folded cuff prevents the cuff from being properly inflated thus preventing effective placement of the device. In addition, the commonly placed 15 mm connector at the proximal end of the airway tube can also prevent the insertion of other devices into the airway tube.
There is therefore a need for an improved laryngeal airway device that does not suffer from these shortcomings.